Thirty patients having had anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BPTB) autograft and thirty patients having had ACL reconstruction with hamstring (HS) autograft were enrolled. All procedures were performed using an endoscopic technique with identical postoperative rehabilitation, such that the only variable was the type of graft and its fixation. Lateral and 45 degrees posteroanterior (PA) weightbearing radiographs were performed in each patient at 6-12 (mean 9) months postoperatively in the HS group and 9-22 (mean 13) months postoperatively in the PT group. The sclerotic margins of the tunnel were measured at the widest dimension of the tunnel by a single observer and were compared with the initially drilled tunnel size after correction for radiographic magnification. For the BPTB group, all bone plugs appeared to be incorporated radiographically. On the femoral side, the bone plug was incorporated at the roof of the intercondylar notch, such that no tunnel measurement could be made. Well-defined sclerotic margins were always present at the tibial and femoral tunnels for the HS group and at the tibial tunnel for the BPTB group. The mean percentage increase in tunnel size in the PA view was 9.7%+/-14.7% for the BPTB tibial tunnel, 20.9%+/-13.4% for the HS tibial tunnel, and 30.2%+/-17.2% for the HS femoral tunnel. The mean percentage increase in tunnel size in the lateral view was 14.4%+/-16.1% for the BPTB tibial tunnel, 25.5%+/-16.7% for the HS tibial tunnel, and 28.1%+/-14.7% for the HS femoral tunnel. The difference in HS and BPTB tibial tunnel expansion on both the PA and lateral views was statistically significant (P = 0.003 and P = 0.01, respectively). Inter-observer variability was excellent with an intra-class correlation coefficient of 0.92. Tunnel expansion was significantly greater following ACL reconstruction using HS autografts than in those using BPTB autografts. The points of fixation for the HS grafts are at a greater distance from the normal insertion site and biomechanical point of action of the ACL than the points of fixation for BPTB grafts. We believe that this greater distance creates a potentially larger force moment during graft cycling which may lead to greater expansion of bone tunnels.

Cartilage damaged by trauma has a limited capacity to regenerate. Current methods for treating small chondral defects include palliative treatment with arthroscopic debridement and lavage, reparative treatment with marrow stimulation techniques (e.g. microfracture), and restorative treatment, including osteochondral grafting and autologous chondrocyte implantation. Larger defects are treated by osteochondral allografting or total joint replacements. However, the future of treating cartilage defects lies in providing biologic solutions through cartilage regeneration. Laboratory and clinical studies have examined the treatment of larger lesions using tissue engineered cartilage. Regenerated cartilage can be derived from various cell types, including chondrocytes, mesenchymal stem cells, and pluripotent stem cells. Common scaffolding materials include proteins, carbohydrates, synthetic materials, and composite polymers. Scaffolds may be woven, spun into nanofibers, or configured as hydrogels. Chondrogenesis may be enhanced with the application of chondroinductive growth factors. Finally, bioreactors are being developed to enhance nutrient delivery and provide mechanical stimulation to tissue-engineered cartilage ex vivo. The multi-disciplinary approaches currently being developed to produce cartilage promise to bring the dream of cartilage regeneration in clinical use to reality.

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Background In total knee arthroplasty (TKA) periprosthetic joint infection (PJI), irrigation debridement (I&D) with component retention is a treatment option with a wide variation in reported failure rates. The purpose of this study was to determine failure rates, outcomes, and factors that predict failure in I&D for TKA PJI. Methods A multicenter observational study of patients with a TKA PJI and subsequently undergoing an I&D with retention of components was conducted. The primary outcome was failure rate of I&D, where failure was defined as any subsequent surgical procedures. Results 216 cases of I&D with retention of components performed on 206 patients met inclusion criteria. The estimated long-term failure rate at 4 years was 57.4%. Time-to-event analyses revealed that the median survival time was 14.32 months. Five-year mortality was 19.9%. Multivariable modeling revealed that time symptomatic and organism were independent predictors of I&D failure. Culture negative status had a higher hazard for failure than culture positive patients. When primary organism and time symptomatic were selected to produce an optimized scenario for an I&D, the estimated failure rate was 39.6%. Conclusions I&D with retention of components has a high failure rate, and there is a high incidence of more complex procedures after this option is chosen. The patient comorbidities we investigated did not predict I&D success. Our results suggest that I&D has a limited ability to control infection in TKA and should be used selectively under optimum conditions.

Level III, diagnostic study.

Background Prosthetic joint infection is an uncommon but serious complication of total knee arthroplasty (TKA). Control of infection after TKA is not always possible, and the resolution of infection may require an above-knee amputation (AKA). Questions/purposes The purpose of this study was to determine the etiology of AKA and the functional outcomes of AKA after infected TKA. Methods We retrospectively reviewed 35 patients who underwent AKA after an infected TKA. The amputations were performed an average of 6 years (range, 21 days to 24 years) after primary TKA. There were 19 females and 16 males with a mean age of 62 years (range, 26-88 years). Patient demographic information, comorbidities, surgical treatments, cultures, and culture sensitivities were recorded. Complications and functional status, including SF-12 and activities of daily living questionnaires, after AKA were also studied. The minimum followup was 7 months (mean, 39 months; range, 7-96 months).

Background Treatment of chronic periprosthetic joint infections (PJIs) after TKA is limited to fusions, above-theknee amputations (AKAs), revision TKA, and antibiotic suppression and is often based on the patient's medical condition. However, when both fusion and AKA are options, it is important to compare these two procedures with regard to function. Questions/purposes Do patients receiving a knee fusion for PJI after TKA have better function compared to patients receiving an AKA?Methods We retrospectively reviewed patients who were eligible for either fusion or AKA after PJI TKA. Thirtyseven patients underwent a fusion for PJIs after TKA between 1999 and 2010. Nine patients died postoperatively and eight patients were lost to followup, leaving 20 patients. Patients completed a specialized questionnaire about their fusion, and functional capability was assessed by the SF-12. We compared fusions to a previously published group of six patients who underwent AKA for recurrent PJI after TKA.

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